1. Field of the Invention
The present invention relates in particular to an image reading apparatus and an image processing apparatus suitable for reading the image on an image reading medium by manual operation.
2. Description of the Related Art
In recent years, an image reading apparatus which reads an image on an image reading medium when it is moved over the image reading medium by the operator are widely used, apart from the well-known stationary (placed on a table or the like) image reading apparatus. Such an image reading apparatus (the movable one) is smaller in size and weight and has the advantage that the image can be read easily in comparison to the stationary image reading apparatus. It is expected that the demand of this type of apparatus will increase in the future. Although this type of apparatus is advantageous, because the apparatus is manually moved over the image, the speed with which the apparatus is moved naturally varies. Such variations in the moving speed deteriorate the quality of the read image. Accordingly, a manually operated image reading apparatus free of such a disadvantage is desired.
Image reading apparatuses, which optically read an image on an image reading medium (hereafter, a paper. However, an image reading medium is not limited to a paper) are roughly divided into three types including flat bed type, sheet feed type and handy type. The flat bed type and the sheet feed type of image reading apparatuses are stationary types of apparatuses in which a sheet(s) of paper(s) from where an image is to be read is set in a tray or the like provided in the apparatus. On the other hand, the handy type of apparatus is one that is manually moved (slide) on a sheet of paper from where an image is to be read. The size of such a handy type of image reading apparatus can be made smaller than that of the other two types of image reading apparatuses. Accordingly, the handy type of image reading apparatus can be easily carried with a laptop type of personal computer or a PDA (portable information terminal) and used where and when required.
FIG. 12 is a perspective view showing an example of an external appearance of a conventional image reading apparatus. All the important parts of the image reading apparatus are provided inside a housing 10 which is substantially rectangular in shape. One side of the housing 10, that is, image reading surface 10a comes into contact with a paper when reading an image from the paper. A transparent protective cover 12 is provided on a part of the image reading surface 10a which protects the optical parts of an image reading section. The image reading section is described later with reference to FIG. 10.
A roller 13 is provided on the image reading surface 10a and detects the amount of movement of the image reading apparatus when the apparatus is moved on the paper for reading the image. This roller 13 constitutes a part of an amount of movement detection section 22 described later. The roller 13 rotates in accordance with the amount of movement of the apparatus. A rotary encoder (not shown) detects an amount of rotation of the roller 13. A connector 14 is connected to the housing 10 through a cable 15. This connector can be inserted into a connector section 16a of a PC card 16. The PC card 16 is a card type interface which can be inserted into a card slot of an information processing system (for example, a personal computer, not shown).
Operation of the conventional image reading apparatus will be explained below. When reading the image on the paper, the user places the image reading apparatus in such a position that the image reading surface 10a touches the paper at the reading start position on the paper. In this condition, the roller 13 also touches the paper. The user then presses a switch once (not shown).
The user starts the operation of reading the image by sliding the case 10 on the paper in the direction of scanning. Frictional force is generated between the surface of the paper and the surface of the roller 13 due to which the roller 13 starts rotating. As the roller 13 starts rotating, detection of the amount of movement is also started.
When the amount of movement pulse which is output when the amount of movement is equal to the width of one line is input, then image data of one line is read. If the speed with which the case 10 is moved exceeds a speed specific to the image reading apparatus, many amount of movement pulses are input, however, image data of only one line is read.
When the case 10 is caused to slide to the reading end position on the paper, the user presses the switch once more so as to end the reading operation.
As described above, in the conventional image reading apparatus, if the speed with which the case 10 is moved exceeds the speed specific to the image reading apparatus, then the amount of movement pulses are output many times. In other words, in such a case, the case 10 is moved for a distance which is equivalent to the width of many lines. However, although the case 10 is moved for a distance which is equivalent to the width of many lines, image data of only one line is actually read.
Accordingly, in the conventional image reading apparatus, image data of only one line is displayed where in reality image data of many lines should have been displayed. As a consequence, the image gets contracted and the quality of the image degrades.
In order to solve the above-mentioned problem, the following measures are taken in the conventional image reading apparatus. That is, an alarm is generated when the scanning speed crosses the specified value, or it is mentioned in the operation manual(s) that the scanning should be performed steadily and at a constant slow speed. In the actual image reading operation, however, there is a tendency for the scanning speed to increase without notice as the operation is repeated several times. Therefore, it cannot be said that the measures taken in the conventional image reading apparatus are the effective solutions to the problem.
It is an object of the present invention to provide an image reading apparatus and an image processing apparatus that are free from the effect of variation in the scanning speed and capable of producing an image not contracted in the scanning direction.
In order to achieve the above-mentioned object, the image reading apparatus, according to one aspect of the present invention, comprises an image reading unit, an amount of movement detection unit, and an image data generation unit. Once the read operation is started, the image reading unit reads one line of the image on the image reading medium at predetermined time intervals and outputs it as image data. Further, the amount of movement detection unit detects the moving mount of the image reading unit relative to the image reading medium. In the case where the number of lines of the image data read is reduced below the number of lines moved as the result of the scanning speed increased beyond a specified value, the image data generation unit generates the image data corresponding to the shortage to attain the number of lines equal to the number of lines moved.
Thus, even in the case where the scanning speed is higher than a specified value, the image data of the same number of lines as the number of lines moved by the image reading unit are generated by the image data generation unit, and therefore an image free of contraction in the scanning direction is obtained.
Further, the image data generation unit generates image data for a plurality of the lines based on the image data of one line in the image reading unit when the image reading unit has moved for a plurality of lines within one time period. Thus, when the image reading unit moves for a plurality of lines during one time period, i.e., when the scanning speed is greater than a specified value, the image data generation unit generates image data for a plurality of lines based on the image data of one line acquired by the image reading unit. Accordingly, the image data for a plurality of lines is generated based on the image data of one line in the image reading unit, and therefore even in the case where the scanning speed is higher than a specified value, an image free of contraction in the scanning direction is obtained.
Further, the image data generation unit duplicates the image data of one line in the image reading unit thereby to generate the image data for a plurality of lines when the image reading unit moves for a plurality of lines during one time period. Thus, when the image reading unit moves for a plurality of lines during one time period, i.e., when the scanning speed is greater than a specified value, the image data generation unit generates image data for plurality of lines by duplicating the image data of one line acquired by the image reading unit. Accordingly, the image data of a plurality of lines is generated by duplicating the image data of one line acquired by the image reading unit, and therefore even in the case where the scanning speed is higher than a specified value, an image free of contraction in the scanning direction is obtained.
Further, a storage unit and a transfer unit are provided. The transfer unit causes the storage unit to store the image data in the image reading unit and the image data generated by the image data generation unit, reads the image data from the storage unit and transfers the image data to an external device through an interface. Thus, the image data to be transferred to an external device are stored in the storage unit, and after being read from the storage unit by the transfer unit, transferred to the external device through an interface. Therefore, the data can be transferred to the external device independently of the reading speed of the image reading unit or the processing speed of the image data generation unit. Also, according to the fourth aspect, the data transfer speed is independent of the reading speed or the processing speed, and therefore an interface of low transmission speed can be used, thereby improving the versatility of the image reading apparatus.
The image reading apparatus according to another aspect of the present invention comprises an image reading unit, an amount of movement detection unit, a transfer unit, and an image data generation unit. The image reading unit reads one line of the image on the image reading medium at predetermined time intervals, and outputs them as image data. The amount of movement detection unit detects the amount of movement of the image reading unit relative to the image reading medium. The transfer unit transfers the detection result of the amount of movement detection unit together with the image data acquired by the image reading unit to the image data generation unit through the interface. Thus, when the number of lines of the image data read is reduced below the number of lines moved as the result of the scanning speed being increased beyond a specified value, the image data generation unit generates image data corresponding to the shortage so as to attain the same number of lines as the number of lines moved. Further, the image data is generated in the image data generation unit so that the amount of data generated in the image reading unit is minimized and, hence, the size and cost of the image reading apparatus can be reduced.
The image processing apparatus according to still another aspect of the present invention comprises an image reading unit, an amount of movement detection unit, and an image data generation unit. Once the read operation is started, the image reading unit reads one line of the image on the image reading medium at predetermined time intervals and outputs it as image data. Further, the amount of movement detection unit detects the moving mount of the image reading unit relative to the image reading medium. In the case where the number of lines of the image data read is reduced below the number of lines moved as the result of the scanning speed increased beyond a specified value, the image data generation unit generates the image data corresponding to the shortage to attain the number of lines equal to the number of lines moved.
Thus, even in the case where the scanning speed is higher than a specified value, the image data of the same number of lines as the number of lines moved by the image reading unit are generated by the image data generation unit, and therefore an image free of contraction in the scanning direction is obtained.
The image processing apparatus according to still another aspect of the present invention comprises an image data generation unit and the image data is received from an image processing apparatus. The image data generation unit obtains the image data for the missing lines.